Storage apparatuses which provide large-scale data storage areas by using magnetic recording media such as a large number of hard disk drives (Hard Disk Drives, hereinafter referred to as “HDDs”) are becoming widely utilized. As the data storage area expands, the capacity of each file data and the like to be stored therein also increases, and there arises a demand for the data transfer path used for data I/O to demonstrate high data transfer performance.
In this type of storage apparatus, the data I/O processing between a host computer utilizing the storage apparatus and storage media such as HDDs in the storage apparatus, that is, the processing of data write requests and data read requests from the host is performed by a storage control device (hereinafter referred to as a disk controller (DisK Controller, DKC) as conventionally used) and, to the data transfer inside the DKC and between this DKC and a channel adapter (CHannel Adapter, CHA) which performs communication control between the DKC and the host, or between the DKC and a disk adapter (DisK Adapter, DKA) which performs the communication control between the DKC and the recording media such as HDDs, in place of the conventional parallel transfer method such as, for example, PCI (Peripheral Component Interconnect) bus, the serial transfer method represented by, for example, PCI Express (registered trademark, hereinafter referred to as “PCIe”) is being adopted. This is due to the occurrence of technical problems such as that the control of signal synchronizing timing by the conventional parallel transfer method is difficult, and the like because of demand for high speed data transfer.
When adopting a data transfer path by PCIe to the storage apparatus, ensuring the reliability and the availability as a storage apparatus becomes a problem. For example, Patent Literature (PTL) 1 discloses a configuration where, in the PCIe communication system, even if a failure occurs to a route complex coupled among multiple endpoints via a PCIe switch in a tree structure and a change of the routing information is made in the PCIe switch, a response can be returned to the data transmission source before the change.